This application is for the support of the Coordinating Center for the proposed extension of the ongoing Natural History of Congenital Heart Defects Joint Study. According to the original plan, the patient follow-up was to be complete by June 30, 1973, and the present grant periods in the various centers will end variously in late 1973 and early 1974. These arrangements do not provide for the conduct of final analyses of the data. It is now proposed to extend the study until a common closing at the end of 1975. This would permit a three-month extension for the attainment of the originally scheduled final examination, a mail- telephone closing survey which would add up to seven years to the follow-up, and an orderly conduct of the analyses.